U.S. patent application number 11/367159 was filed with the patent office on 2007-09-06 for camera housing with self-cleaning view port.
Invention is credited to Edwin Michael Gyde Heaven, Kari Kristen Hilden, Patrick Koropatnick.
Application Number | 20070206942 11/367159 |
Document ID | / |
Family ID | 38458627 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070206942 |
Kind Code |
A1 |
Gyde Heaven; Edwin Michael ;
et al. |
September 6, 2007 |
Camera housing with self-cleaning view port
Abstract
Apparatus for maintaining an unobstructed view for visual
monitoring equipment comprises a housing to isolate the visual
monitoring equipment from an external environment. An inlet to the
housing is connectable to a source of gas under pressure for
cooling and cleaning purposes. At least one outlet to the housing
defines a view port to allow the visual monitoring equipment to
acquire images external to the housing and to allow gas to exit the
housing. The outlet constricts the flow of gas leaving the housing
resulting in acceleration of the gas through the outlet to form an
exit jet that maintains the outlet unobstructed by debris. The
housing is simple in construction with few moving parts resulting
in reliable and efficient operation.
Inventors: |
Gyde Heaven; Edwin Michael;
(North Vancouver, CA) ; Koropatnick; Patrick;
(West Vancouver, CA) ; Hilden; Kari Kristen; (West
Vancouver, CA) |
Correspondence
Address: |
KOLISCH HARTWELL, P.C.
200 PACIFIC BUILDING
520 SW YAMHILL STREET
PORTLAND
OR
97204
US
|
Family ID: |
38458627 |
Appl. No.: |
11/367159 |
Filed: |
March 3, 2006 |
Current U.S.
Class: |
396/287 ;
348/E5.026 |
Current CPC
Class: |
G03B 17/02 20130101;
H04N 5/2252 20130101; G01N 21/15 20130101; G01N 2021/151
20130101 |
Class at
Publication: |
396/287 |
International
Class: |
G03B 17/18 20060101
G03B017/18 |
Claims
1. Apparatus for maintaining an unobstructed view for visual
monitoring equipment comprising: a housing to isolate the visual
monitoring equipment from an external environment; an inlet to the
housing connectable to a source of gas under pressure; at least one
outlet to the housing defining a view port to allow the visual
monitoring equipment to acquire images external to the housing and
to allow gas to exit the housing, the at least one outlet
constricting the flow of gas resulting in acceleration of the gas
through the outlet to form an exit jet that maintains the outlet
open and unobstructed.
2. The apparatus of claim 1 in which the housing comprises a
generally cylindrical enclosure having first and second ends, the
first end being formed with the inlet and the second end being
formed with the at least one outlet.
3. The apparatus of claim 1 in which the at least one outlet
comprises a pinhole aperture having a diameter in the range of
about 1 to 10 mm.
4. The apparatus of claim 3 in which the visual monitoring
equipment comprises a camera equipped with a pinhole lens selected
to match the dimensions of the pinhole aperture.
5. The apparatus of claim 1 in which the at least one outlet
comprises an opening having a diameter in the range of about 11-50
mm.
6. The apparatus of claim 5 in which the visual monitoring
equipment comprises a camera equipped with a 8-48 mm zoom lens
selected to match the dimensions of the opening.
7. The apparatus of claim 1 in which the visual monitoring
equipment is positioned adjacent the at least one aperture to
achieve a wide angle view through the aperture.
8. The apparatus of claim 1 in which the visual monitoring
equipment comprises a CCD array analog camera.
9. The apparatus of claim 1 in which the visual monitoring
equipment comprises a CCD array digital camera.
10. The apparatus of claim 1 including a sealing system to prevent
contaminants from entering the housing in the event that the source
of gas under pressure is lost.
11. The apparatus of claim 10 in which the sealing system
comprises: a sealing element within the housing to separate the
interior of the housing into a first region proximate the outlet
into which contaminants may enter in the event that the source of
gas under pressure is lost, and a second region housing the visual
monitoring equipment which remains contaminant free; and a
labyrinth passage about the sealing element to communicate the
second region with first region to allow gas to exit the housing by
the outlet, the lens of the visual monitoring equipment protruding
through the sealing element into the first region.
12. The apparatus of claim 11 in which the sealing element
comprises a gasket extending across the housing.
13. The apparatus of claim 12 including a gasket support member to
support and retain the gasket in place.
14. The apparatus of claim 11 in which the labyrinth passage
comprises an annular region about the outer perimeter of the
sealing element defined by an annular shoulder having a plurality
of passages dimensioned to permit the passage of gas under pressure
flowing from the second region to the first region while physically
blocking passage of contaminants moving from the first region to
the second region.
15. The apparatus of claim 14 including a diversion element to
communicate gas flowing from the second region to the first region
by diverting gas flow into the annular region about the sealing
element.
16. The apparatus of claim 1 in which the source of gas under
pressure is a source of filtered air.
Description
FIELD OF THE INVENTION
[0001] This invention relates generally to visual monitoring
systems used to observe a site of interest, particularly in
industrial processes, and, more particularly to a housing for an
image capturing camera that protects the camera from the
environment external to the housing and maintains an unobstructed
view port for the camera.
BACKGROUND OF THE INVENTION
[0002] Visual monitoring systems, particularly those developed for
use in industrial environments where conditions for observation of
objects of interest are often detrimental to reliable viewing,
generally require means to maintain a clear view of the objects of
interest. These environments commonly have ambient conditions that
result in the monitoring equipment being coated in short order in
layers of opaque material that are by-products of the industrial
process under observation. For example, in the paper making
industry, stray paper fibres that are an inevitable part of the
manufacturing process tend to be deposited on, and build up to
cover all stationary equipment adjacent to the processing line. The
ambient conditions are also inappropriate for reliable operation of
electronic monitoring equipment such as video or still cameras. The
environments can include high temperatures, caustic or corrosive
atmospheres, condensing liquid and directed sprays, and mechanical
contaminants and debris that will individually or in combination
cause the camera equipment to malfunction or to fail to provide the
required view.
[0003] Visual monitoring systems will typically protect the image
acquisition equipment or camera in an enclosure to provide means to
control the environment in which the camera operates. This
enclosure is substantially sealed from the external environment and
is equipped with a covered view port through which the camera can
capture images of the external environment. Generally, the
enclosure will have a manual or automatic system to maintain a
clear view port for the camera. Many such systems rely on recessed
view ports and/or a sheet of air that is operated intermittently or
continuously to prevent debris or other contaminants from blocking
the view port. For example, U.S. Pat. No. 4,969,035 to Dawson
discloses the use of a gas jet to prevent blocking of a pin hole
aperture adjacent a camera window with debris to permit viewing of
the interior of a furnace or similar high temperature environment.
Published US Patent Application No. 20030210906 to Peterson et. al.
teaches the use of intermittent bursts of air to clean a cover
positioned adjacent a camera protected with an enclosure. Published
US Patent Application No. 20050276599 to Kajino et al. discloses
the use of air streams directed past the lens of a camera sealed in
a housing to prevent condensation built up from blocking the view
of the camera.
[0004] In another approach, U.S. Pat. No. 5,394,208 to Campbell
discloses an enclosure for a camera that relies on creation of a
pressurized enclosure interior and formation of a vortex flow
through a camera view port in the enclosure to prevent blocking of
the view port.
[0005] U.S. Pat. No. 6,362,889 to Mustonen shows the use of a
continuous air stream that flows through a camera housing and
across the camera lens to prevent accumulation of blocking
debris.
SUMMARY OF THE INVENTION
[0006] The present invention employs a new approach that relies on
a high velocity jet of air exiting from a pressurized housing to
maintain a clear and unobstructed view port for visual monitoring
equipment mounted inside the housing.
[0007] Accordingly, the present invention provides apparatus for
maintaining an unobstructed view for visual monitoring equipment
comprising:
[0008] a housing to isolate the visual monitoring equipment from an
external environment;
[0009] an inlet to the housing connectable to a source of gas under
pressure;
[0010] at least one outlet to the housing defining a view port to
allow the visual monitoring equipment to acquire images external to
the housing and to allow gas to exit the housing, the at least one
outlet constricting the flow of gas resulting in acceleration of
the gas through the outlet to form an exit jet that maintains the
outlet unobstructed.
[0011] The pressurized gas serves the dual function of cooling the
visual monitoring equipment and creating a cleaning jet that keeps
the viewing aperture unobstructed by debris and prevents
contamination of the interior of the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Aspects of the present invention are illustrated, merely by
way of example, in the accompanying drawings in which:
[0013] FIG. 1 is a perspective view of a camera housing according
to a preferred embodiment of the present invention from a first end
showing the camera view port;
[0014] FIG. 2 is a perspective view of the camera housing of FIG. 1
from an opposite second end showing access ports to the interior of
the housing;
[0015] FIG. 3 is an exploded view of the camera housing according
to a first embodiment;
[0016] FIG. 4 is an exploded view of the camera housing according
to a second embodiment including a sealing system to prevent
contamination of the interior of the housing; and
[0017] FIG. 5 is a detail sectioned view through the sealing
system.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] Referring to FIGS. 1 and 2, there is shown a first
embodiment of the apparatus 2 of the present invention for
maintaining an unobstructed view for visual monitoring equipment.
The apparatus is intended for use particularly in industrial
processes for monitoring various manufacturing processes and
equipment in environments which may include high temperatures,
caustic or corrosive atmospheres, condensing liquid and directed
sprays, and mechanical contaminants and debris that will
individually or in combination cause unprotected monitoring
equipment to malfunction or to fail to provide the required view.
It will be understood that the apparatus of the present invention
finds application in any environment where reliable monitoring of a
process is required.
[0019] The apparatus 2 generally comprises a housing 4 to isolate
the visual monitoring equipment from an external environment. The
visual monitoring equipment 5 (FIG. 3) may include a video or still
photography camera such as a CCD array analog or digital camera or
any other equipment capable of providing image data. In the
illustrated embodiment, the housing comprises a generally
cylindrical enclosure having a first end 6 and second end 8. First
end 6 is formed with a plurality of access ports 10 to allow access
to the interior of the housing for lines 11 providing power and
control signals to the visual monitoring equipment 5 mounted within
the interior of the housing. Access ports 10 also accommodate video
signal lines that transmit image data collected by the monitoring
equipment 5. Lines 11 are sealed at their point of entry into first
end 6 using standard sealing techniques. The exterior of housing 4
includes a mounting bracket 7 to allow the housing and camera to be
conveniently mounted at the desired angle to a location on the
equipment being monitored. It will be understood that alternative
mounting brackets or arrangements are possible.
[0020] First end 6 also includes a housing inlet 12 connectable to
a source of gas under pressure 14 via line 15. The pressurized gas
introduced into the interior of the casing via inlet 12 serves to
maintain the temperature of the interior within an acceptable
temperature range for reliable operation of the visual monitoring
equipment 5. In many cases, this will involve the pressurized gas
cooling the camera equipment, but it is also possible in very cold
environments that the pressurized gas will perform a warming
function. In many applications, the source of gas under pressure 14
will comprise a source of filtered air, however, it will be readily
apparent to a person skilled in the art that other gases can be
used.
[0021] The second end 8 of housing 4 is formed with at least one
outlet 20 which defines a view port to allow the visual monitoring
equipment 5 to acquire images of a site of interest external to the
housing. Outlet 20 also allows the pressurized gas entering the
housing via inlet 12 to exit the housing. Outlet 20 is dimensioned
to constrict the flow of gas exiting the housing with the result
that the gas is accelerated through outlet 20 to form an exit jet
that maintains the outlet clear and unobstructed by debris or other
contaminants.
[0022] In a preferred arrangement, outlet 20 comprises a pinhole
aperture having a diameter in the range of about 1 to 10 mm. Such
an arrangement uses visual monitoring equipment in the form of a
camera 5 equipped with a pinhole lens 23 selected to match the
dimensions of the pinhole aperture. Pinhole lens 23 can be a fixed,
varifocal, or zoom lens.
[0023] In an alternative embodiment, outlet 20 comprises a larger
opening having a diameter in the range of about 11-50 mm. In this
arrangement, the visual monitoring equipment can be a camera that
uses a larger lens such as an 8-48 mm zoom lens selected to match
the dimensions of the opening.
[0024] In all cases, the lens of the camera is positioned adjacent
the outlet 20 to achieve a clear, preferably wide angle, view
through the outlet. To facilitate proper positioning of the camera
within the housing, an elongate mounting plate 24 is optionally
provided to permit slidable movement of the camera along the
longitudinal axis of the housing such that the lens is properly
positioned directly behind outlet 20.
[0025] In the first embodiment of FIG. 3, the second end 8 of
housing 4 is formed from a generally circular end plate 28 formed
with a central outlet 20. Plate 28 is retained against retaining
ring 29 by an outer locking ring 34. Internal to plate 28, an inner
circular plate 30 is provided having a plurality of holes
therethrough. Central hole 31 provides an opening through which
pinhole camera lens 23 protrudes to allow the plate to stabilize
and support the lens. The other holes 33 provide passages through
plate 30 for flow of pressurized gas to the second end 8 of the
housing. Retaining ring 29 is formed with an inwardly extending
shoulder 35 against which inner plate 30 abuts when retaining ring
29 is fitted over an edge 37 of the housing.
[0026] To ensure reliable operation, the housing of the present
invention requires must be sealed and pressurized during normal
operation to ensure that contaminants do not enter the interior of
the housing. In this respect, O-ring seals are preferably used
between sections of the housing to ensure an adequate seal. In
addition, outlet 20 preferably includes a mechanism to ensure that
contaminant ingress is prevented in the event that the supply of
pressurized gas is lost. This may take many forms depending on the
internal configuration of the apparatus. For example, a one way
valve 32 or pressurized release plug may be used. Where the
internal components are not affected by the external contaminants,
the return of air pressure will self-clear the opening. If the
internal components are affected by contaminants, then they need to
be protected from the ingress of contaminants by a physical barrier
such as internal component housings, internal component enclosures,
internal component protective covers, or barriers at the outlet
which will interpose themselves when pressure is lost but not
obstruct the view through the opening. By way of example, the
visual monitoring equipment 5 and the attached lens 23 may be
independently sealed using a waterproof material against any
potential contaminant ingress into the housing from the external
environment.
[0027] FIGS. 4 and 5 show a second embodiment of the apparatus of
the present invention which includes an exemplary sealing system
for preventing contaminants from entering the housing in the event
that the supply of pressurized gas is lost. Parts of the apparatus
that are identical to the parts of the first embodiment are
identified by the same reference number. In the second embodiment,
the second end 8 of the housing 4 includes a plate 28 with outlet
20 which is retained against an edge of retaining ring 29 by
locking ring 34. In this case, the inwardly extending shoulder 35
of retaining ring 29 is formed with a plurality of passages 40 to
allow pressurized air to flow through the shoulder. In this
embodiment, the open centre of retaining ring 29 is blocked by a
series of plates and gaskets that fit about the camera lens 23 to
prevent contaminants from entering the housing. In particular, the
open centre of retaining ring 29 is blocked by a front gasket
holder 42, a flexible gasket 44, and a gasket spacer ring 46 which
are all formed with aligned central openings 48 to accommodate lens
23 of the camera. The front gasket holder 42, flexible gasket 44
and gasket spacer ring 46 co-operate to define a sealing element
within the housing through which the lens 23 of the camera
protrudes. The sealing element acts to separate the interior of the
housing into a first region adjacent the outlet into which
contaminants can infiltrate in the event of a loss of gas pressure
and a second, sealed region which is always free of
contaminants.
[0028] Optionally, front gasket holder 42 is formed with a
rearwardly extending edge 50 into which gasket 44 and gasket spacer
ring 46 fit to form a combined sealing unit. This sealing unit fits
over camera lens 23 which protrudes through the aligned central
openings 48 of the individual elements. Flexible gasket 44 performs
the sealing function while rigid front gasket holder 42 and rigid
gasket spacer ring 46 support the gasket therebetween. The front
gasket holder and gasket space ring also act to support the camera
lens extending therethrough.
[0029] A labyrinth gas flow diversion passage is created about the
outer perimeter of the sealing element to permit flow of gas under
pressure out of the housing while preventing contaminants from
entering the second, sealed region of the housing in the event that
gas pressure is lost. Front gasket holder 42 is shaped and
dimensioned to fit against an inner side of shoulder 35 of
retaining ring 29 to define an outer annular region 52 between
gasket holder edge 50 and retaining ring 29. Annular region 52 is
best shown in FIG. 5 which is a cross-sectional view of the
assembled sealing system. To divert pressurized gas into annular
region 52, a flow diversion ring 54 is mounted in front of gasket
spacer ring 46. Flow diversion ring 54 comprises a flat, annular
body 55 with a central opening for the passage of pressurized gas.
The face of annular body 55 immediately adjacent gasket spacer ring
46 is formed with a series of radial channels 56 that extend from
the inner edge of the opening of the body to the outer edge. As
shown by arrows 58 in FIG. 5, pressurized gas flowing parallel to
the longitudinal axis of the housing is diverted to flow radially
outwardly when the flow reaches gasket spacer ring 46. The diverted
gas flow is directed by radial channels 56 into annular region 52.
Passages 40 through shoulder 35 allow the diverted flow to exit
annular region 52 into the region 60 behind end plate 28. The
pressurized gas then flows through outlet 20 as a jet which
maintain the outlet clear of debris.
[0030] In the event that gas pressure is lost, any contaminants
that enter outlet 20 will tend to be confined in region 60 between
end plate 28 and front gasket holder 42. Passages 40 are
dimensioned to permit free flow of gas under pressure, however, any
contaminants such as liquids or particles will tend not move
through the passages toward the sealed interior of the housing.
When gas pressure is restored, the gas flow will tend to eject any
contaminants back out outlet 20 in a self-cleaning operation.
[0031] As shown in FIG. 3 or 4, the apparatus of the present
invention, particularly housing 4, is optionally of a modular
construction to allow interchanging of different parts. For
example, ends 6 and 8 of the housing are preferably circular plates
that are sealably fastened into place using O ring seals 38 in
combination with threaded or snap on retaining rings 34. This
allows for different end plates formed with differently dimensioned
outlets 20 or access ports 10 to be used in the event that the
camera 5 within the housing is changed. Section 36 of housing 4 can
also be formed into different lengths or multiple sections can be
stacked together to vary the overall length of the housing to
accommodate camera and lens units of different longitudinal
dimensions. This provides further flexibility in ensuring that the
camera lens 23 is always positioned adjacent outlet 20.
[0032] The supply of pressurized gas 14 is preferably controlled to
ensure that the supply remains on during normal operation. This
control can also involve varying the gas flow so that the velocity
of the jet exiting outlet 20 remains constant even when different
sized openings are used with the housing. The range of preferred
jet velocities is determined by both the density of the pressurized
gas (usually air) and the mass and surface area presented by
contaminants. The minimum preferred jet velocity would then be the
free fall velocity of any contaminants. This can range from as
little as 1 m/s for light powders or flakes to as high as 100 m/s
for dense compact contaminants such as wet pulp.
[0033] Although the present invention has been described in some
detail by way of example for purposes of clarity and understanding,
it will be apparent that certain changes and modifications may be
practised within the scope of the appended claims.
* * * * *